Joule Thief 101

[tinman]

 author=MileHigh link=topic=8341.msg478758#msg478758 date=1459169878]
         

The cycle time is 75 microseconds for one trace (spike) and 60 microseconds for the second trace (collector).

What planet are you on MH?.
The first scope shot was across the 1k ohm resistor--to show you that the death spike is still there--read bloody post.
The spike trace--blue base trace is shorter than than the collector current trace-the yellow trace.
Can you not follow a very simple schematic and scope placements?--do you not know that voltage leads current in an inductor,and thus the reason for the blue trace(base trace) being slightly shorter than the yellow trace-collector current trace in time period-->voltage leads current MH-you doofus.



 

Was the CVR for the collector trace in the same place when you captured the spike trace?

All was taken on the same circuit--nothing changed.

Or did you have two different circuits for each test and that's why the cycle time is different between the two?Oops you don't say anything about that and even the best Brad secret decoder ring can't help in this situation.

No-as stated above-->same circuit.
It is not my fault you do not understand the fact that voltage lead's current with inductors,and not my fault you cant work out the time difference between voltage and current rise.
The transistor switches off(blue trace) at the very same time the CVR on the colletor shows 0 volts across it. Then the voltage from the battery show across L1 and L2 before(BEFORE MH) current starts to flow,and you get a voltage drop across the collector CVR.

Why didn't you put the CVR for the collector trace on top of L1

For the very simple reason that we are looking for your current flow through the collector junction,into the base junction,due to junction breakdown.
You ask the dumbest of questions some time's.

You are second-guessing our mutual original conclusion (yourself, myself, Picowatt) about the death spike and now you are questioning me about your own second guessing?

No-i said the current flow through the base in the opposite direction,was due to junction capacitance-->and PW said that is quit possible. So dont go bullshitting again,as your about to learn something--guru.

Remember in your ever present quest to insist that you are never wrong that you were insisting that the reverse current spike was normal?

It is normal when you wind a JT toroid so as it will operate at a lower voltage--there is no set MH winding parameters for the JT.

Did you even try to reduce the number of turns in L2 to see if the reverse current spike would go away in the original setup?  Brain fry indeed.

Many time's. But why would i wind a JT to stop functioning at 320mV,when i can wind one that keeps running right down to 180mV?

Not surprisingly and as expected Brad, what you have shown is incomplete and it is a complete shambles.

Whats not suprising, is that you dont know that voltage appears across an inductor,before current flows through it. If you did,you wouldnt be asking as to why the two time basses are different.
Biiiggg blunder there MH--again.

The battery was run down to 500 odd mV in the last scope shot's,so here are the new ones with a fresh battery--1.6 volts.
The first scope shot is with the probe ground on one side of the 1k base resistor,and the probe tip on the other side of the 1k base resistor--is that clear enough MH?
The second scope shot is as the circuit depic's-->the circuit is not changed at all during the tests--is that clear MH?

Minimum voltage across 1 ohm CVR at the collector is 0mV-->no reverse current is flowing from the collector ,through the collector/base junction,and out through the base-->none.

Wrong my ass.

Yes-wrong your ass
Please try again MH.

Brad

[tinman]

Dose the below explain the time difference of around 20uS MH.
Do you see now how the CH2 spike shot is taken across the 1k ohm resistor(as it should be) to show the reverse current spike, is based on current flow rise time,and how the second scope shot,CH2 is based around voltage rise time. And did you read in my post that the scope is being triggered by CH2?

Are there any more questions MH?.
Where is the reverse current flow at the collector?


Brad

[tinman]

MH

I have decreased the VPD on CH1,and inverted it.
I have also moved it across,so as it lines up with the current triggered death spike shot.

Dose this make it any clearer as to what is happening ?

Brad

[tinman]

 author=MileHigh link=topic=8341.msg478746#msg478746 date=1459159374]
Brad:

The source of the current flow causing the breakdown of the junction is L1.  So when you talk about the "two options for L2s current path" anybody that has a Brad Secret Decoder Ring knows that what you are really saying is the "two options for L2s current path after that current is supplied from the discharge from L1."   It's just the usual scrambled brains in action.

We are talking about the event of the transistor collector-base junction breaking down and current being observed flowing in the reverse direction through the base.

You have avoided responding to this issue because Dr. Brainfry is supposedly infallible.  Push has come to shove and instead of acknowledging that you failed to think through your statements before you posted them and admit that you were in fact wrong, now you are instead having a good freak out and going nuts in an attempt to still not admit that you are dead wrong.  Dr. Brainfry is having a brain seizure.

Brad:

When  you act like you are acting, I think it could be an indication that you have some serious psychological problems.

You are second-guessing our mutual original conclusion (yourself, myself, Picowatt) about the death spike and now you are questioning me about your own second guessing?

I never agreed to anything about collector/base breakdown voltage,and as far as im aware,neither did PW. If he did say that,then he may learn something to.

At this point in time MH,i would strongly suggest you go back and re read what PW said.

You should be looking in the mirror when you make your insult's toward me--as those stated above-along with a basket full of others.\


Brad

[picowatt]

Exceeding the base-emitter reverse breakdown voltage of Q1 does not turn on the collector-emitter junction. 

The spike seen in the recent "death spike" capture looks more like a Miller current spike than as being due to Vbe breakdown current.

In these recent captures, there is no evidence that the base voltage is exceeding the Vbe breakdown voltage (I believe Tinman measured his 2N3055's as breaking down around 20 volts)

PW